1. Field of Invention
The present invention relates to a machine tool member, in particular to a machine tool spindle structure having a device for inspecting a working state.
2. Related Art
Machine tools are machinery for manufacturing various machines and processing equipment, and may be categorized into metal cutting machine tools and metal molding machine tools according to functions. The metal cutting machine tools include lathes, drilling machines, milling machines, grinding machines, and planning machines, and the metal molding machine tools include punching machines and shearing machines. A machine tool is composed of several parts, in which in the drilling machine, the milling machine, the grinding machine, the planning machine, and other machine tools uses the rotational cutting movement, and the critical part affecting the processing quality is a machine tool spindle. Therefore, the accuracy of the machine tool spindle required by the machine tool manufacturers is quite strict.
During the operation of the machine tool, the material characteristics of the processed workpiece, the addition of the cutting fluid, and other practical processing situations may directly affect the processing quality. In early times, the working state of the machine tool spindle is practically inspected after the processing is finished. If the finished pieces cannot meet the accuracy demand, the machine tool spindle is adjusted or maintained, but the loss is generated. In order to solve the problem, some manufactures of the machine tools propose that an accelerometer, a thermometer, a strain gauge, or other inspecting devices are assembled outside the machine tool spindle, so as to measure the vibration, the temperature variation, the processing output torque, and other working parameters during the processing process. However, during the processing process, the cutting waste exists or the cutting fluid is sputtered near cutter, so the inspecting devices cannot be assembled adjacent to the cutter. Thus, the working parameters measured by the inspecting devices cannot really reflect the working state of the cutter, and it is not helpful to monitor the processing state in real time or improve the processing quality.
In order to solve the problem that the inspecting device of the machine tool spindle cannot really reflect the working state of the cutter, U.S. Pat. No. 7,289,873 has disclosed a sensor system for a cutting machine tool (hereafter referred to as Case 873). In the sensor system for the cutting machine tool provided in Case 873, a power supply unit is disposed in the machine tool, so as to supply the power required by at least one sensing chip in the machine tool. The at least one sensing chip may measure the torque, the noise, and other working states of the machine tool, and a data transmission unit wirelessly transmits the data to a receiving unit out of the machine tool. In Case 873, the sensing chip is disposed in the machine tool, so as to acquire the relatively precise working parameters of the actual working state, and wirelessly transmit the working parameters to the external receiving unit in real time for acquiring relevant information. In detail, in Case 873, the electric power required by the sensing chip, the microprocessor, and the data transmission unit is supplied by the power supply unit, which generates the electric power by using an induction coil. That is, when the machine tool spindle rotates, a relative change of the magnetic field generates the electric power. In order to solve the problem that it is impossible to directly dispose power lines in the machine tool, the power supply unit of Case 873 adopts the induction coil design. However, in Case 873, the induction coil, the sensing chip, and the data transmission unit are quite adjacent to one another, the magnetic field generated by the power supply unit will also directly interfere with the sensing chip or the data transmission unit, such that sensing chip cannot acquire the accurate data, or the wireless transmission of the data is affected.